Safety switch means for machine having a power-stroking operation



April 18, 1967 M. CAIN G. SAFETY SWITCH MEANS FOR MACHINE HAVING A POWER-STROKING OPERATION Filed Sept. 15, 1965 2 Sheets-Sheet 1 5 S 10 I .34 z

54 -xi4 I 52-5 I 40 q) I v 3a so so x1 RT INVENTWI, GARDINER M. CAIN BY firM/l W ATTORNEY April 18, 1967 G. M. CAIN 3,315,049

SAFETY SWITCH MEANS FOR MACHINE HAVING A POWER-STROKING OPERATION Filed Sept. 15, 1965 2 Sheets-Sheet 2 as r 36 F 36 N 416 56 34 1/ 34 34/ TLE 22 D .-i .4 5Q i #w Q W H? 32 44 42 44 42 44 42 F19. Z 3 F131. 4

INVENTOR 1201mm M. 6AM! BY {M4 W ATTORNEY A 5] C 6 46 51 40% r22 has United States Patent SAFETY SWITCH MI iANS FOR MACHINE HAV- ING A POWER-STROKING OPERATION Gardiner M. Cain, 1318 Hoyt Ave., Indianapolis, Ind. 46203 Filed Sept. 15, 1965, Ser. No. 487,475 12 Claims. (Cl. 20061.42)

This invention relates to a safety means, for machines having a power-stroking operation such as presses, riveters, stakers, and the like.

More particularly, the concepts of the safety-means provide, subsequent to actuation of the power-stroke by the operator, an initial and automatic stroke-preparatory feeling or testing of the danger region through which the power-stroke is to be made; and if no foreign object or obstruction is encountered, the power-stroke is automatically actuated and permitted, but actuation of the powerstroke is not actuated or permitted if such an obstruction is encountered by the feeling or sensing apparatus.

According to the invention, the activation by the .operator does not directly energize a non-recallable powerstroke operation,'but rather, operator-activation energizes only the said feeling or sensing apparatus. This automatic sensing apparatus then performs its sensing task, and, if no obstruction is found, it in turn energizes the power-stroke, automatically, as an incident to its sensing movement completed without an encountering of an obstacle.

The advantages of safety to an operators limbs, :or to inanimate dies, punch-heads, and the like, are obvious. The energization of the machine power stroke is by a secondary circuit, wholly uncontrolled and unreachable by the operator, and energizable only by the sensing apparatus having found the danger zone free from obstruction, thus assuring that human error will not initiate or permit a power stroke when there is any obstruction in the danger zone.

This safety means achieves safety without need of a knocking arm which knocks away an obstruction, those arms having been known to injure an operator by their very knocking motion and slamming effect. Instead, the safety means of this invention is quite light and harmless to the obstruction, and prevents injury by simply not energizing the power stroke rather than by trying to knock away the obstruction. Neither does the safety means employ an attempted stopping or braking of a power stroke already started and moving; rather it causes the power stroke to not begin, and eliminates thereby the disadvantages of trying to absorb the kinetic energy of a moving ram.

Moreover, even in machines which do not require constant operator-feeding, or which do not involve actuation by an operator of individual power strokes, the concepts provide an initial zone-testing prior to each power stroke; thus avoiding breakage by preventing a continuation of power-stroking if an object should happen by any means to fall into the power-stroke path.

The description so far is somewhat introductory; and

the concepts, features, and advantages of the invention will more fully appear in the following more detailed description of embodiments to illustrate the inventive concepts, taken in conjunction with the accompanying somewhat schematic drawings, in which:

FIG. 1 is a pictorial view of a press device embodying safety means according to concepts of the present invention, portions of a control housing being broken away to illustrate interior details;

FIGS. 2, 3 and 4 are schematic views, in smaller scale, illustrating the vertical position and operational relationships of the parts;

More particularly, FIG. 2 illustrates the parts in a position in which the senser means has not been actuated, and is in a fully retracted position above the press-bed and the work supported thereon;

FIG. 3 illustrates the parts in a position in which the senser means has been actuated, and has moved its full amount of travel, this full travel having indicated there was no obstruction above or on the work-piece; and this full travel has permitted the senser means to actuate the automatic control switch to actuate the press-ram;

FIG. 4 illustrates the parts in a position in which the travel of the senser means has been blocked by an object lying on the work-piece; and, in this travel-blocked position, the senser means does not actuate the automatic control switch, and thus the ram of the press is not energized and does therefore not stroke; and

FIG. 5 is a fragmental view of the control rod, illustrating modified adjustment means.

As shown in the drawings, the invention is illustrated in conjunction with an electrically-actuated press 10.

The press 10 is shown diagrammatically as having a base-table or bed 12 having an upright supporting column 14 which carries a fixed press-head 16; and from the head 16 there extends downwardly an axially-movable power ram 18 which carries Whatever working head (not shown) is desired.

Omitted for clarity are work-holding means which would be secured to the bed 12 to retain the workpiece 20 (FIGS. 2 through 4). Also, for ease of understanding, and because the distinction between two-wire and a three-wire circuitry is not relevant to the inventive concepts, the electric power for actuation of the press-ram 18 is shown as by a two-wire circuit 22, the power for which comes from an external two-wire electric supply 24. Relays may be used as desired.

Safety switches 26 and 28 are located on the left-hand and right-hand .portions of the press-bed 12, and are wired in an operational series electric circuit 30, requiring the operator to use both hands to depress them simultaneously, and thus better assure that his hands will not be in the path of travel of the press-ram 18 when it is actuated by means yet to be described.

The components identified numerically so far in this description form no part of the present invention, except in their relation to and their co-operation with the safety means of the invention.

According to concepts of the present invention, there is provided a safety means including a feeler or senser means 32 which is caused to feel or test the work-area prior to any possibility of actuation of the press-ram 18; and only if the work-area is operationally free of any foreign object can the senser 32 cause the power-ram 18 to be actuated. This safety is now explained in greater detail.

The senser 3-2, shown illustratively in the general shape of a rectangular ring, the axis of which is co-axial with the axis of travel of the power ram 18, is carried at the foot of a control rod 34 which is thrust downwardly by a solenoid 36, wired in series with hand-switches 26 and 28, and thus actuated by the simultaneous closure of those switches.

A spring 38 holds the control rod 34 upwardly except upon energization of solenoid 36, the spring being shown as operatively disposed around rod 34 and between an abutment collar 40 adjusta'bly fixed to rod 34 and a fixed abutment shown provided by the lower wall 42 of a control housing or box 44. The control box 44 is fixedly located with reference to the press-bed 12, being fixed to the press-head 16 in the embodiment shown.

Inside the control box 44, there is also provided a control means shown as an abutment 46 adjustably fixed to rod 34, and a normally-open electric switch 48 fixedly located in the box 44. Adjustment of position of rodabutment 46 is illustrated by a pin 49 which passes through an opening in abutment 46 and into a selected one of rod-openings 50.

When the switch-element 51 of switch 48 is moved to switch-closing position (such movement being shown in FIG. 4 to be automatically caused by engagement of rodabutment 46 with switch-element 51 when the rod 34 has moved its full travel), the closure of switch 48 closes press-operating circuit 22.

Safety is provided by this combination of components, as is illustrated by FIG. 2, and a comparison of FIGS. 3 and 4, now to be further explained.

In understanding this safety feature, it will be first observed in FIGS. 2 and 3, that the components have been positioned so that, in the upper or retracted position of control rod 34, the vertical distance A between the lower surface of rod-abutment 46 (reference plane B) and the plane of closure of switch-element 51 of switch 48 (reference plane C) is as great as the distance D between the lower surface of rod-abutment 40 (reference plane E) and the fixed abutment at reference plane F provided by the top of spring 38 when in fully-compressed condition on the box-wall 42.

The distance D thus governs the length of full travel of control-rod 34 (adjustability of abutment 40 on rod 34 being indicated by a pin 52 passed through an opening in rod-abutment 46 and into a selected one of the rodopenings 54); and, only when the control-rod 34 has moved the full distance D (which is the length of actuation-travel A), d es rod-abutment 46 close the pressactuating switch 48.

(If the switch 48 is sturdy enough, the travel-blocking effect of switch 48 itself as it is engaged by rod-abutment 46 may be utilized to permit the distance A to govern the length of full travel of control-rod 34, the rod-abutment 40 in that case being used only as a seat against which the spring 38 bears.)

The adjustment of distances A and D (or simply of distance A, as just mentioned), those distances governing the travel of control-rod 34 and senser 32, is such as to permit the senser 32 to move as far as desired to obtain the work-area-testing of the particular operation. Accordingly, those distances A and D will be set to be as much as the distance G between the lower surface of the senser 32 (reference plane H) and the upper surface of the work-piece 29 or press-bed 12 (reference plane 1) according to how low the senser 32 is desired to test.

(In FIGS. 2 and 3, the reference plane I has been illustratively selected as that of the top of the work-piece 20, permitting holding means to underlie the bounds of the senser ring 32 within the elevational limits of the work-piece; but with objects of less diameter than the diameter of senser ring 32, the senser 32 ring could be set to go to a lower reference plane I, the ring 32 in that situation freely passing along and outside of the workpiece 20 as the feeler-ring 32 descends.)

Adjustment of senser-arm 32 on control-rod 34 is shown in FIG. 2 as by a pin 56 which passes through an opening in the holding-ring 58 of senser-arm 32 and into a selected one of rod-openings 60.

However, in FIG. 5, such adjustment is shown as alternatively provided internally of control box 44, as by a control-rod 34 being made of telescoping sections 34:: and 34b, adjustably pinned by a pin 62 which passes through an opening 64 in section 34a and into a selected one of openings 66 in section 3412. This adjustment provides more foolproofness; for with all the adjustments being in the box 44, the adjustments could be made by a set-up man who then locks the box 44, and the operator could not then change the settings.

Turning to FIG. 3, it will be seen that full downward travel of rod 34 permits rod-abutment 46 to actuate switch 48, actuating the power stroke of the press-ram 18. But this is a safe actuation; for the full travel of senser 32 has meant that there was no obstruction or foreign object on or above the work 20 in the path of the ram 18.

However, if there is such an obstruction, as shown in FIG. 4 by the obstructing object 68, the travel of senser 32 (and thus also of control rod 34) is blocked by engagement of the senser 32 with object 68; and thus the rod-abutment 46 cannot operatively engage the switch 48 to actuate press-ram circuit 22.

An over-zealous but accident'prone operator cannot overcome the safety effect by yanking control-rod 34 downwardly in an effort to obtain closure of switch 48, for such movement is blocked by the same obstruction 68', and only when the obstruction 68 is removed can rod 34 be lowered to effect closure of switch 48.

Breakage cannot be made by engagement of the senser 32 with the obstruction 68, for the force of the control rod 34 in its downward travel is quite small, wholly insignificant in comparison to the force of the press'ram 18 in a power stroke. Even a slight resistance to downward travel of senser 32 and control-rod 34 blocks their travel, and prevents actuation of the press-ram 18.

Although the inventive concepts, embodying a senser which tests the work-area, and which actuates the pressram upon finding the work-area free from obstruction (power-stroke operation being specifically dependent upon that finding of freedom of obstruction) are shown in conjunction with electric circuitry for both the handswitches 26 and 28 and the power circuit 22, the inventive concepts are not limited to circuitry of electric nature for either or both those circuits.

And neither are the concepts limited to any particular power source for the press-ram; although desirably the press-actuation is rapid enough, and of a non-delayed nature, such that no obstruction can enter the stroke-zone after switch 48 is closed and the senser 32 departs that zone. If slow ram-action is a characteristic of the machine, a delay means is desirably provided for the control rod 34, maintaining the senser 32 in its lowered position (FIG. 3) where it performs a bathing service.

The concepts permit modifications to suit the specific operation. For example, the control-rod 34 can be supported to follow an arcuate path instead of the axial path in the illustrative embodiment. Moreover, camming or screw-type means may be provided to achieve a rotary sweeping effect of the senser-arm 32 if desired.

High safety is also achieved by the fact that the operator cannot mechanically overcome the safety feature (as he can do in safety means which merely try to force him to have both hands at specific safe places, as in the switch arrangement shown by switches 26 and 28, for one or both of them can be mechanically held down and taped). With the concepts of the present invention, there simply is no way for the operator to overcome or bypass the safety feature, short of sawing off the control-rod 34, or jumping the switch 48, the circuit 22 of which is desirably encased in metallic conduit.

Adjustment to accommodate differing work situations is easily effected, the adjustable connections here shown illustratively as pin connections being of adjustable screwtype or of set-screw or other type if more minute adjustments are desired.

It is thus seen that the novel concepts of the present invention provide a safety means having several advantages as set forth, and avoiding disadvantages of other safety apparatus, the advantages here generally relating to high safety assurances, foolproofness, and positiveness of operation, providing a preparatory sensing of the danger zone prior to ram-activation.

Accordingly, it will thus be seen from the foregoing description of the invention according to the illustrative embodiments, considered with the accompanying drawings, that the present invention provides a new and useful safety means, having desired advantages and characteristics, and accomplishing its intended objects, including those hereinbefore pointed out and others which are inherent in the invention.

It will be understood that modifications and variations may be etfected without departingifrom the scope of the novel concepts of the present invention; accordingly, the invention is not limited to the specific form or arrangement of parts herein described or shown.

What is claimed is:

1. Safety means for a machine having a power stroke in which a member moves along a path, comprising:

a senser means;

a control rod connected at one end to said senser means;

motive means located at the other end of said control rod for moving said senser means from a first position to a second position, the path of said movement of the senser means co-inciding with the path of movement of said power stroke member so that any obstruction in said path of said power stroke member will be sensed by said sensing means;

said motive means being of low force to permit the senser means to stop its said movement upon encountering an obstruction present in the sensing path of said sensing means;

a control means which when actuated actuates the power stroke of the machine, said control means being located in the path of movement of an actuator means;

said actuator means being mounted intermediate the ends of said control rod, and associated with said senser means for actuating said control means when said senser means is in its said second position, assuring that no such obstruction has been encountered;

an operator-controlled actuation means connected to and actuating the said motive means for the said senser means, assuring that the sensing operation of the said sensing means will be performed preliminarily to the power stroke of the machine, and subsequent to actuation by the operator of the operatorcontrolled actuation means.

2. Safety means for a machine having a power stroke in which a member moves along a path, comprising:

a senser means;

a control rod connected at one end to said senser means;

motive means located at the other end of said control rod for moving said senser means from a first position to a second position, the path of said movement of the senser means co-inciding with the path of movement of said power stroke member so that any obstruction in said path of said power stroke member will be sensed by said sensing means;

said motive means being of low force to permit the senser means to stop its said movement upon encountering an obstruction present in the sensing path of said sensing means;

a control means which when actuated actuates the power stroke of the machine, said control means being located in the path of movement of an actuator means;

said actuator means being mounted intermediate the ends of said control rod, and associated with said senser means for actuating said control means when said senser means is in its said second position, assuring that no such obstruction has been encountered;

the said actuator means being operatively spaced from the said control means in a manner to provide that the senser means must move a pre-determined amount of sensing travel prior to actuating the said control means.

3. Safety means for a machine having a power stroke in which a member moves along a path, comprising:

a senser means;

means moving said senser means from a first position to a second position, the path of said movement of the senser means operatively co-inciding with the path of movement of said power stroke member so that any obstruction in said path of said power stroke member will be sensed by said sensing means;

said moving means being of low force to permit the senser means to stop its said movement upon encountering an obstruction present in the sensing path of said sensing means,

a control means which when actuated actuates the power stroke of the machine; means associated with said senser means for actuating said control means when said senser means is in its said second position, assuring that no such obstruction has been encountered;

said moving means being a solenoid;

first circuit means for actuating said solenoid;

said associated means and said control means comprising an abutment and a switch means, one of which is fixed onto the senser means and one of which is stationary relative thereto;

second circuit means for the said control means;

the second circuit means being energized by the said switch means operatively independent of the first circuit means.

4. Safety means for a machine having a power stroke in which a member moves along a path, comprising:

a senser means;

a control rod connected at one end to said senser means; a

motive means located at the other end of said control rod for moving said senser means from a first position to a second position, the path of said movement of the senser means co-inci-ding with the path of movement of said power stroke member so that any obstruction in said path of said power stroke member will be sensed by said sensing means;

said motive means being of low force to permit the senser means to stop its said movement upon encountering an obstruction present in the sensing path of said sensing means;

a control means which when actuated actuates the power stroke of the machine, said control means being located in the path of movement of an actu ator means;

said actuator means being mounted intermediate the ends of said control rod, and associated with said senser means for actuating said control means when said senser means is in its said second position, assuring that no such obstruction has been encountered;

co-operating abutment means, one of which is operatively fixed to the said senser means and one of which is stationary with respect thereto, for limiting the amount of travel of said sensing means to the said second position thereof.

5. Safety means for a machine having a power stroke in which a member moves along a path, comprising:

a senser means;

a control rod connected at one end to said senser means;

motive means located at the other end of said control rod for moving said senser means from a first position to a second position, the path of said movement of the senser means co-inciding with the path of movement of said power stroke member so that any obstruction in said path of said power stroke member will be sensed by said sensing means;

said motive means being of low force to permit the senser means to stop its said movement upon encountering an obstruction present in the sensing path of said sensing means;

a control means which when actuated actuates the power stroke of the machine, said control means being located in the path of movement of an actuator means;

said actuator means being mounted intermediate the ends of said control rod, and associated with said senser means for actuating said control means when said senser means is in its said second position, assuring that no such obstruction has been encountered.

6. Safety means for a machine having a power stroke in which a member moves toward a work area, comprising:

a senser member;

movable means supporting said senser member in a first position operatively away from said work area and toward and into a second position operatively in said work area;

motive means associated with said movable means for moving said senser member between said two positions;

said motive means being of low force to permit said senser member to stop its said movement upon encountering an obstruction present in its path of movement;

a control means which when actuated actuates the power stroke of the machine, said control means being located in the path of movement of an actuator means;

said actuator means being movable with said movable means associated with said senser member for actuating said control means when said senser member is in its said second position, assuring that no such obstruction has been encountered.

'7. Safety means for a machine having an operational effect along a path, comprising:

senser means movable to a location operatively in said path;

a movable support means movably supporting said senser means;

motive means for moving said support means and thus also said senser means to said location, the senser means being of a nature to detect an obstruction if existing along said path, thus the movement of said senser means into said location assuring said path is free from obstruction;

control means for energizing said motive means;

actuator means operatively connected to said movable support means for actuating the operational effect of the machine along said path, but operable only upon the senser means having reached said location, assuring that the operational effect cannot be actuated if there were any obstruction preventing the said sensing means from having reached said location.

8. Safety means for a machine having an operational efiect along a path, comprising:

senser means movable to a location operatively in said path;

a movable support means movably supporting said senser means;

motive means for moving said support mean sand thus also said sensing means into said location;

a control means for actuating the power stroke of the machine;

said senser means being responsive to the presence of an obstruction in said path to prevent actuation by said control means, the control means being cooperative with said movable support member to be actuatable to energize said operational effect only if said senser means has reached said location without sensing any such obstruction.

9. Safety means for a machine having an operational effect along a path, comprising:

first and second actuating means for the machine and a senser means; movable support means movably supporting said senser means;

the first actuating means being conditional in its effect of actuating the operational effect of the machine, and dependent upon the operation of the senser means;

said senser means being operative to sense said path for obstructions, automatically, upon actuation of the said first actuating means, and, upon sensing a said obstruction, is operative through said movable support means and said second actuating means to prevent operational activation of said second actuating means, but which, upon completion of its sensing operation without sensing an obstruction, automatically and through said movable support means actuates said second actuating means.

10. Safety means for a machine having an operational efiect along a path, comprising:

first and second actuating means and a senser means;

said senser means being actuated by said first actuating means and operative to sense said path for obstructions, automatically, upon actuation of the said first actuating means, and, upon sensing a said obstruction, is operative through the below-mentioned control means to prevent operational activation of said second actuating means;

shielding means, and control means positioned with the said control means being unable to actuate the operational efiect of the machine except in response to the senser means.

11. Safety means for a machine having an operational effect along a path, comprising:

machine-actuator means for actuating said operational effect;

control means for said machine-actuator means, and operative in one position to actuate said machineactuator means, and in another position to render said machine-actuator means inoperative to actuate the operational efiect of the machine; senser-actuator means controllable by the operator;

a senser means actuated by said senser-actuator means,

said senser means being operative to sense said path for obstructions, and, if it senses a said obstruction, is operative through said control means to prevent said actuating means from achieving actuation of said operational effect, but the senser means, upon completion of said sensing operation without sensing such an obstruction, automatically and through said control means actuates said actuating means, thereby actuating said operational effect of said machine along the said path.

12. Safety means for a machine having an operational effect along a path, comprising:

means for actuating said operational effect;

9 l0 senser-actuator means; trolling the operative activation of the operational a senser means which is actuated by said senser-actuator effect of the machine, and

means, and is operative to sense said path for obstructh id t l means being able to a t t th lions, and Which, if it Senses a Said Obstruction, is operational effect of the machine except in response operative through the below-mentioned control 5 to the senselmean means to prevent said operational-effect actuating means from achieving actuation of said operational effect;

shielding means, and control means positioned with FOREIGN PATENTS respect to said shielding means so as to be inaccessi- 731,051 6/1955 Great Britain ble to the machine operator, the control means being 10 responsive to the senser means to operatively control BERNARD GILHE ANY Primary the actuation of the operational effect of the machine, the said control means being the sole means for con- BAKER, Assistant Examine!- References Cited by the Examiner 

1. SAFETY MEANS FOR A MACHINE HAVING A POWER STROKE IN WHICH A MEMBER MOVES ALONG A PATH, COMPRISING: A SENSER MEANS; A CONTROL ROD CONNECTED AT ONE END TO SAID SENSER MEANS; MOTIVE MEANS LOCATED AT THE OTHER END OF SAID CONTROL ROD FOR MOVING SAID SENSER MEANS FROM A FIRST POSITION TO A SECOND POSITION, THE PATH OF SAID MOVEMENT OF THE SENSER MEANS CO-INCIDING WITH THE PATH OF MOVEMENT OF SAID POWER STROKE MEMBER SO THAT ANY OBSTRUCTION IN SAID PATH OF SAID POWER STROKE MEMBER WILL BE SENSED BY SAID SENSING MEANS; SAID MOTIVE MEANS BEING OF LOW FORCE TO PERMIT THE SENSER MEANS TO STOP ITS SAID MOVEMENT UPON ENCOUNTERING AN OBSTRUCTION PRESENT IN THE SENSING PATH OF SAID SENSING MEANS; A CONTROL MEANS WHICH WHEN ACTUATED ACTUATES THE POWER STROKE OF THE MACHINE, SAID CONTROL MEANS BEING LOCATED IN THE PATH OF MOVEMENT OF ANI ACTUATOR MEANS; SAID ACTUATOR MEANS BEING MOUNTED INTERMEDIATE THE ENDS OF SAID CONTROL ROD, AND ASSOCIATED WITH SAID SENSER MEANS FOR ACTUATING SAID CONTROL MEANS WHEN SAID SENSER MEANS IS IN ITS SAID SECOND POSITION, ASSURING THAT NO SUCH OBSTRUCTION HAS BEEN ENCOUNTERED; 